Piero diCosimo,also known as Piero di Lorenzo(circa 1462-1522) was a Florentine Renaissancepainter. The son of a goldsmith, Piero was born in Florence and apprenticed under the artist Cosimo Rosseli, from whom he derived his popular name and whom he assisted in the painting of the Sistine Chapel in 1481.

In the first phase of his career, Piero was influenced by the Netherlandish naturalism of Hugo van der Goes, whose "Portinari Triptych" (now at the Spedale of Santa Maria Novella in Florence) helped to lead the whole of Florentine painting into new channels. From him, most probably, Cosimo acquired the love of landscape and the intimate knowledge of the growth of flowers and of animal life. The manner of Hugo van der Goes is especially apparent in the "Adoration of the Shepherds", at the Berlin Museum.

During his lifetime, Cosimo acquired a reputation for eccentricity, a reputation enhanced and exaggerated by later commentators such as Giorgio Vasari, who included a biography of Piero di Cosimo in his "Lives of the Artists". Reportedly, he was frightened of thunderstorms, and so pyrophobic that he rarely cooked his food; he lived largely on hard-boiled eggs, which he prepared 50 at a time while boiling glue for his artworks. He also resisted any cleaning of his studio, or trimming of the fruit trees of his orchard; he lived, wrote Vasari, "more like a beast than a man".

If, as Vasari asserts, he spent the last years of his life in gloomy retirement, the change was probably due to preacher Girolamo Savonarola, under whose influence he turned his attention once more to religious art. The death of his master Roselli may also have had an impact on Piero's morose elder years. The "Immaculate Conception with Saints" and the "Holy Family" best illustrate the religious fervour to which he was stimulated by Savonarola.

With the exception of the landscape background in Rosselli's fresco of the "Sermon on the Mount", in the Sistine Chapel, there is no record of any fresco work from his brush. On the other hand, Piero enjoyed a great reputation as a portrait painter. However, the paintings for which he is best known are appropriately idiosyncratic: fanciful mythological inventions, inhabited by fauns, centaurs, and primitive men. There is sometimes a spirit of low comedy about these delightful works.

Contemporary documents reveal that Cosimo died of plague on April 12, 1522.